Paper-Marking Test for Chimpanzee: Simple Control for Social Cues

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Science  24 Nov 1978:
Vol. 202, Issue 4370, pp. 903-905
DOI: 10.1126/science.202.4370.903


A series of paper-marking tests, modeled after tests widely applied to humans, was administered to Sarah, a "language"-trained chimpanzee (Pan troglodytes). The test format was simple, economical, and controlled for social cues. The ape successfully made same-similar-different judgments on pictures of familiar objects when up to four questions were presented at the same time. Performance remained satisfactory on same-different judgments of novel pictures of alphabetic characters. Throughout the series of tests, the subject showed a superiority on same judgments.